This project has been designed to accomplish two major goals: 1) to evaluate the mechanism of HIV-associated immunopathic platelet destruction (HIV-ITP), and 2) to determine the relevance of elevated platelet immunoglobulin levels in the HIV infected state. The specific aims of this proposal will test the hypothesis that the mechanism of HIV-ITP is not due to the increased platelet load of immunoglobulins (or immune complexes), but is most likely due to autoantibody.